Explosives Flashcards
Initial response for explosion incident is:
- Gain control of the scene
Preservation of life and treatment of casualties first priority
Identify victims
Important to have forensic awareness training
Post explosion incident scene control:
- Gain control of scene
- Place cordon around scene, radius of 100-200m
- Point of explosion would be the center point
- Radius will depend on debris field and environment
Purpose of Cordon is:
- Preserve the scene
- Allows systematic and effective recovery of evidence
- Control access and movement
- Allow forensic recovery to happen in undisturbed and safe way
Goals for recovery after explosive incident is:
- Determine cause of explosion
- Construction, components and functioning of explosive device
- Nature of explosive charge
- Recover physical and chemical evidence
Place recovered items from explosion in airtight nylon bag:
- Time and date of recovery
- Recovery location
- ID of person recovering evidence
- Unique identifier
- Log item out of scene
Two essential components of explosive device:
- Explosive charge
- Means to initiate charge
Parts of explosive device may include:
- Explosive train/ various explosives to achieve detonation
- Electrical components/ wires, batteries, leds
- Timing devices
- Shrapnel/ nails and screws
- Sensors/ proximity and movement
- Switches/ mechanical and electronic
Types of explosions:
- Mechanical/ buildup of pressure until vessel fails
- Chemical/ chemical reaction from heat, light gases
- Nuclear/ splitting or fusing of atoms; energy from heat and X-rays
- Electrical/ high energy arcs that generate heat for explosion;energy of
reaction energizes atoms of target material until breakdown occur
Ex: lighting, short circuit
Primary effect of explosion:
- Blast wave (pressure)
- Fragmentation
- Incendiary (thermal component)
Blast wave is:
- Pressure wave that radiates outward from point of explosion
- May be produced by expanding gases and combustion
- Causes the most damage
- Radiates outward rapidly; distance increases, speed and pressure drop
- At point of explosion, vacuum created air is pushed away by pressure
wave
Fragmentation is:
- Device broken into pieces by blast or when objects are attached
to the outside or included inside a device to increase blast
damage to kill and injure personnel - Common in IEDs and hand grenades
- Low explosives (cause large rectangular shaped fragments)
- High explosives ( cause small triangular shaped fragments)
Fragmentation types are:
- Primary (shrapnel or fragments from initial explosion)
- Device casing or objects attached to outside
Secondary (when primary fragments stroke something and impart directional energy to that object)
Primary effect of explosion:
Incendiary Thermal Effect
- High temperature from explosion
- Maybe localized at point of explosion
- Can be done remotely from hot fragments hurled outward from point of explosion
- Most incendiary explosions will cause incendiary effect of some type
Improvised Explosive Device (IED) consist of:
- Detonator
- Booster
- Main Charge
Elements of IEDs:
- Explosive
- Initiation System
- Container
- Binding material
- Shrapnel and other hazardous material
IED components are:
- Switch
- Initiator
- Explosive
- Power source
Essential components of explosive device:
- Explosive charge
- Means of initiating charge
- Post explosion; basis of forensic recovery.
Four major elements of explosion:
- Rapid increase in gas pressure
- Confinement of pressure
- Rapid release of that pressure
- Damage or change to the confining structure of the vessel
Post explosion recovery:
- High explosive (shattering ability, damage such as irregular fracture provide evidence of detonating explosive; plastic melting and microscopic cratering
- Deflagrating explosives (recovered post explosion in unreacted state; like propellants in pipe bombs; rupture of vessel lead to quenching of reaction resulting in unconsumed explosive charge available for recovery.
Recovery of evidence from bodies:
- Types of injuries received by victims
- Shrapnel (fragments from explosive device may identify it)
- Victims should be examined and X rayed locate, recover and ID source
- Chemical examinations may ID explosive device
Results of explosion:
- Structural damage
- Broken gas lines
- Broken water lines
- Downed electrical lines
- Release/ production of toxic materials
- Biological issues
Primary blast injuries known as PBIs:
- Caused by large pressure differential of blast wave
shearing, implosion and acceleration/deceleration injuries - Hollow medium filled tissues such as ears, lungs and GI at higher risk
then solid organs - Total body disruption (TBD); amputation
- Usually occur to victims in close proximity(suicide bombers)
Secondary blast injury (SBI):
- Caused by objects accelerated by explosion
- Velocity (injury potential of projectiles based on magnitude)
- Weight of projectile, distance from source of explosion
- IEDs employ additives such as screws and nails for similar effect
- Account for majority of injuries in survivors
Modes of activation:
- Delay activation
- Victim activation
- Command activation
An explosion is:
A rapid expansion of gases resulting from a chemical or physical action that produces a pressure wave.
Tertiary Blast injury (TBI) is:
- Result of displacement of victim by blast wind.
- Victim propelled along ground, resulting in contusive blunt trauma
- Victim launched through air; may collide with stationary objects.
- Severity of TBI depend on proximity and magnitude of blast.
Quaternary Blast injury :
Result from variety of blast effects
- Burns, chemical and toxic dust poisoning, radiation exposure,
crush injury due to building collapse
